1. Field
This technology pertains generally to dosimetry, and more particularly to systems for collecting and analyzing dosimetry data, and most particularly to dosimetry data collection systems utilizing telecommunications for collecting data.
2. Description of Related Art
Personal dosimetry is used to monitor exposure of individuals to ionizing radiation. This is necessary for workers and visitors in a variety of locations, including nuclear reactors, and radiodiagnostic and/or radiotherapy centers. It may also be necessary for responders to terrorist acts that may involve radioactive material.
Personal dosimeters are typically compact passive devices worn by individuals. Various types of dosimeters are used, most commonly using film, thermoluminescent (TLD), or optically stimulated luminescent (OSL) detectors. One particular type of dosimeter that is highly advantageous is the direct ion storage (“DIS”) dosimeter. The DIS dosimeter is based on a metal oxide field effect transistor (MOSFET). The charge on a floating gate is affected by radiation incident into a chamber surrounding the gate.
The dosimeters must be read at certain times to determine the exposure level of the wearer. While this may be done on site, usually such capability is lacking as readers are expensive. Dosimeters are often sent to a central processing lab where they are evaluated. This is somewhat cumbersome since it involves swapping dosimeters at the site and transporting them back and forth.
A better system would be one in which only the data, and not the physical dosimeter, is sent to a central processing station. A reader could be provided at each site for reading the data from each dosimeter. The data from the reader could then be transmitted electronically to a central station. However, such a system would require many readers located at various sites.
It would be preferable to not have any intermediate readers, but to send the data directly from the dosimeter itself to the central station. It also would be preferable to send this data from a dosimeter to a central station using a communications system based on readily available technology.
Accordingly it is desirable to provide a dosimetry data collection system in which raw data is sent from a dosimeter to a central processing station using readily available communications systems.
Some references of interest are WO/2009/107444 (Fuji Electric Systems) (PCT/JP2009/051451, US2011/0063127) and JPH11-258346 (Aloka Co. LTD.). In these references are the general components of: dosimeters that can communicate, relay devices, and central stations. One reference shows a system where wireless relay devices initiate collection of data from the dosimeters by transmitting a monitor indication request to the dosimeters. With this, the dosimeters are apparently always “on” to receive an interrogation signal whenever it is sent. The other reference shows a system where dosimeters are read at a fixed base station when the dosimeters are in close proximity to the base station. However, since some dosimeters may rarely if ever reach the base station, each dosimeter communicates with other dosimeters when they come into proximity with each other so that any dosimeter that then reaches a base station can provide its own and other dosimeter data. With this design, dosimeters seemingly must always be on to communicate with any other dosimeter when it is in close proximity. Both of these systems because of their “always on” requirements, rapidly drain battery power. Therefore, a need is seen for a dosimeter that is in a dormant state until the need to communicate arises.